Evaluation and Measurement for Vibration in Buildings Part 1, BSI ...

ISO 4866:1990(E)
Licensed copy:HALCROW GROUP LTD, 27/01/2009, Uncontrolled Copy, © BSI
Annex A (informative)
Classification of buildings
A.1 General
This annex provides simplified and helpful
guidelines for classifying buildings according to
their probable reaction to mechanical vibrations
transmitted by the ground.
A dynamic system, for the purposes of this
classification, consists of the soil and strata, in
which are set the foundations (if existing),
together with the building structure itself.
Table A.2 gives 14 simplified classes taking into
consideration the following factors:
— type of construction (as ascertained from
Table A.1);
— foundation (see clause A.5);
— soil (see clause A.6);
— political importance factor.
The frequency range is taken from 1 Hz to 150 Hz
(see also 3.3), which covers most events met in
industrial practice, blasting, piling and traffic.
Shock directly introduced into the structure by
industrial machinery is not included though its
effects at some distance are. Shock produced by
blasting, piling and other sources outside the strict
confines of the structure are not included but the
effects on the structure are. The buildings referred
to exclude very tall structures with more
than 10 storeys.
A.2 Structures involved
A.2.1 The following structures are included in the
classification:
— all buildings used for living and working
(houses, offices, hospitals, schools, prisons,
factories, etc.);
— publicly used buildings (town halls, churches,
temples, mosques, heavier industrial mill-type
buildings, etc.);
— elderly, old and ancient buildings of
architectural, archeological and historical value;
— lighter industrial structures, often designed to
the codes of building practice.
A.2.2 The following structures are not included in
the classification:
— heavier structures such as nuclear reactors
and their adjuncts and other heavy power plants,
rolling mills, heavier chemical engineering
structures, all types of dams, and containing
structures for fluids and granular materials, for
example water towers and tanks, petroleum
storage, grain and other silos, etc.;
— all underground structures;
— all marine structures.
A.3 Definition of classes (see Table A.2)
The classes are defined by taking as a reference a
well maintained building in good repair. The
reference building shall not have any constructional
defects nor shall it have sustained accidental
damage from earthquakes. If the construction does
not fulfil these requirements, it shall be allocated to
a lower class.
The order in which the structural types are
classified depends on their resistance to vibrations,
and also on the tolerances that can be accepted for
the vibrational effects on structures, given their
architectural, archeological and historical value.
Three important elements enter into the reaction of
a structure under the effects of mechanical
vibrations. The three elements are as follows:
— the category of the structure — Table A.1 gives
a preliminary classification of the categories of
structures based on the groups defined in
clause A.4;
— the foundation (see clause A.5);
— the nature of the soil (see clause A.6).
A.4 Categories of structures
A.4.1 Group 1 — Ancient and elderly buildings
or traditionally built structures
The types of buildings considered in this group can
be divided into the two following sub-groups:
a) elderly, old or ancient buildings;
b) all modern buildings constructed in older,
traditional style using traditional kinds of
materials, methods and workmanship.
This group, generally, is of heavier construction and
has a very high damping coefficient, for instance due
to soft mortar or plaster. This group also includes
traditionally resilient structures in earthquake
zones. Buildings in this group seldom have more
than six storeys.
A.4.2 Group 2 — Modern buildings and
structures
The types of buildings considered in this group are
all of modern structure using relatively hard
materials tied together in all directions, usually
light in weight overall, and with little damping
coefficient.
This group includes frame buildings as well as
calculated load-bearing wall kinds. Buildings vary
from being single- to multi-storey. All types of
cladding are included. This group also includes
some older types of buildings which are constructed
using modern materials, tying and damping.
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